perf thread_map: Use readdir() instead of deprecated readdir_r()

commit 3354cf71104de49326d19d2f9bdb1f66eea52ef4 upstream.

The readdir() function is thread safe as long as just one thread uses a
DIR, which is the case in thread_map, so, to avoid breaking the build
with glibc-2.23.90 (upcoming 2.24), use it instead of readdir_r().

See: http://man7.org/linux/man-pages/man3/readdir.3.html

"However, in modern implementations (including the glibc implementation),
concurrent calls to readdir() that specify different directory streams
are thread-safe.  In cases where multiple threads must read from the
same directory stream, using readdir() with external synchronization is
still preferable to the use of the deprecated readdir_r(3) function."

Noticed while building on a Fedora Rawhide docker container.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-del8h2a0f40z75j4r42l96l0@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/tools/perf/util/thread_map.c b/tools/perf/util/thread_map.c
index fd8d4384454c41c9fea6294786df4751bd5d3dfb..4e666b95b87e86c2ca700bc7a1dd49e87d754499 100644 (file)
--- a/tools/perf/util/thread_map.c
+++ b/tools/perf/util/thread_map.c
@@ -93,7 +93,7 @@ struct thread_map *thread_map__new_by_uid(uid_t uid)
        DIR *proc;
        int max_threads = 32, items, i;
        char path[NAME_MAX + 1 + 6];
-       struct dirent dirent, *next, **namelist = NULL;
+       struct dirent *dirent, **namelist = NULL;
        struct thread_map *threads = thread_map__alloc(max_threads);
 
        if (threads == NULL)
@@ -106,16 +106,16 @@ struct thread_map *thread_map__new_by_uid(uid_t uid)
        threads->nr = 0;
        atomic_set(&threads->refcnt, 1);
 
-       while (!readdir_r(proc, &dirent, &next) && next) {
+       while ((dirent = readdir(proc)) != NULL) {
                char *end;
                bool grow = false;
                struct stat st;
-               pid_t pid = strtol(dirent.d_name, &end, 10);
+               pid_t pid = strtol(dirent->d_name, &end, 10);
 
                if (*end) /* only interested in proper numerical dirents */
                        continue;
 
-               snprintf(path, sizeof(path), "/proc/%s", dirent.d_name);
+               snprintf(path, sizeof(path), "/proc/%s", dirent->d_name);
 
                if (stat(path, &st) != 0)
                        continue;